Here are a few examples of such products, Https://spreadtheworld.net/ And Https://newsletteros.com/. - Source: dev.to / almost 3 years ago

Janel Loi's authority putting NewsletterOS and PodcastOS together with No-Code tools informs her new job at On Deck, where she will meet more creators to serve, and also serve them better because she has her ongoing side projects. - Source: dev.to / over 3 years ago

There are some, I've seen Periodical on F-Droid before, but I saw now there's another one called drip. Probably more out there, but both of those are also available on Google Play for people who aren't FOSS nerds like me. Source: about 2 years ago

Do you really need it hosted? Is a private app enough? For example, on Android, there's Periodical and I think it doesn't even have the internet access permission. Source: about 2 years ago

If you have an Android device, Periodical is a simple tracking app that does not have Internet permission so it literally cannot share your data. You can back up its data to a text file to restore if need be, and keep that backup off your device. However, if your phone backs itself up to "the cloud" you could still incriminate yourself. Source: about 2 years ago